Seagrasses play an important ecological role in fisheries production, sediment buildup and stabilization. It has direct value to people as food, feed, green, manure, and medicine. Seagrass species have been found to be potential sources of antibacterial, antifungal and antiinflammatory agents as well as anti-cancer substances by phytochemical investigations. The main aim of this study is to prepare Halophila ovalis extract powder and to determine the antioxidant activities of methanolic plant extract.